Hills of greyville

Fast-expanding steel industry yet to find an effective way to reuse its waste product, slag

The road to Tarkera village in Rourkela offers an unusual sight: grey hillocks amid lush green hills. The strange addition to the landscape is slag, a waste product of the steel industry, which has piled up over decades.

Due to poor waste dumping practices of Rourkela Steel Plant of Steel Authority of India Limited (SAIL), the slag has polluted the air besides occupying huge tracts of land. The story does not end in Odisha. Steel plants across the country have failed to chart out a way to use or dispose of slag.

Slag is produced while separating molten steel from impurities. During the process, the unwanted carbon content in the molten metal is removed as gaseous waste, while impurities like phosphorous and silicon are removed as solid waste. Production of one tonne of steel generates half a tonne of solid waste. Steel slag constitutes 20 to 40 per cent of this solid waste. Given that the annual steel production is increasing at eight per cent, the amount of slag generated by 2020 is estimated to be 25 million tonnes. With no effective disposal plan in sight, the industry has a Herculean task ahead.